The Design And Implement Of Backbone VOIP Session Catching System

In the past few years, with the VOIP service booms, the market sacle of VOIP service increased lagely. Under the impact of the growing of VOIP servie, market share of traditional long distant phonecall servie shriked rapidly. Though the VOIP service increased, it also brings many problems at the same time. For example, lacks of auditing, lacks of information security auditing, many illegal VOIP service providers existed. The VOIP service providers need relabilable, cheaply-price and high perfermence production to help them control and manage the VOIP market. After analysis related productions on the market, I found there is not a suitable production, some productions are expensive and complex, other productions are hard to use or not suitable for large scale network. Therefore, a low-cost, realiable and elasticitied VOIP session audit system is needed.The article is based on the BackBone VOIP-audit project which cooperated by Beijing ZiGuang Green Info company can LiaoNing province CNC. Many research works have been done related with NetWork Data collect and analysis. The main tasks and accomplishments are:1. How to write network related program in Linux platform. Descirpte how to grasp network package by using libpcap. Descirpte the character based data package filter chain arithmetic.2. By using SIP protocol as the example, analysis the process of a SIP session, analysises the structure of SIP packages, analysis the prosibillity to restore a SIP session, the arithmetic of restore a SIP session is also provided.3. Research the hardware which used to duplicate and unpack the SDH package. A rule based, mulit-layer data dispatch resolution is provided.4. Research the data catching preformence problem and gives the resolution. In this article, all softwares are open source software and dispatched under GPL license.